{% load crispy_forms_tags %}
<form method="get">
    <div class='row'>
        <!--
            {{ filter.form.fields }} -->
    {% for f0  in filter.form %}
        <div class='col-md-3'>
            {{ f0 | as_crispy_field}}  
        </div>
    {% endfor %}
    </div>
    <input type="submit" class='btn btn-primary' value='Search'/>
</form>
